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# John traveled the entire 50 km trip. If he travelled the first 20 km o

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Math Revolution GMAT Instructor
Joined: 16 Aug 2015
Posts: 5577
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John traveled the entire 50 km trip. If he travelled the first 20 km o [#permalink]

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02 Mar 2018, 01:21
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Difficulty:

5% (low)

Question Stats:

86% (01:03) correct 14% (01:16) wrong based on 73 sessions

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[GMAT math practice question]

John traveled the entire 50 km trip. If he traveled the first 20 km of the trip at a constant rate 40 km per hour and the remaining trip at a constant rate 20 km per hour, what is his average speed, in km per hour?

A. 20 km/h
B. 23 km/h
C. 25 km/h
D. 26 km/h
E. 27 km/h

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"Only $99 for 3 month Online Course" "Free Resources-30 day online access & Diagnostic Test" "Unlimited Access to over 120 free video lessons - try it yourself" BSchool Forum Moderator Joined: 26 Feb 2016 Posts: 2816 Location: India GPA: 3.12 Re: John traveled the entire 50 km trip. If he travelled the first 20 km o [#permalink] ### Show Tags 02 Mar 2018, 02:00 MathRevolution wrote: [GMAT math practice question] John traveled the entire 50 km trip. If he traveled the first 20 km of the trip at a constant rate 40 km per hour and the remaining trip at a constant rate 20 km per hour, what is his average speed, in km per hour? A. 20 km/h B. 23 km/h C. 25 km/h D. 26 km/h E. 27 km/h If John travels 20 km at 40 km/hr he would take $$\frac{1}{2}$$ hour. The remainder of the trip - 30 km was traveled at 20 km/hr and took a time of $$\frac{30}{20} = \frac{3}{2}$$ hours. The total time taken is 2 hours and the distance traveled is 50 km. Therefore, the average speed at which John travels is $$\frac{50}{2} = 25$$km/h (Option C) _________________ You've got what it takes, but it will take everything you've got CEO Joined: 12 Sep 2015 Posts: 2561 Location: Canada Re: John traveled the entire 50 km trip. If he travelled the first 20 km o [#permalink] ### Show Tags 02 Mar 2018, 07:33 Top Contributor MathRevolution wrote: [GMAT math practice question] John traveled the entire 50 km trip. If he traveled the first 20 km of the trip at a constant rate 40 km per hour and the remaining trip at a constant rate 20 km per hour, what is his average speed, in km per hour? A. 20 km/h B. 23 km/h C. 25 km/h D. 26 km/h E. 27 km/h Average speed = total distance/total travel time total distance = 50 km total travel time = time spent driving at 40 kmh + time spent driving at 20 kmh time = distance/speed So, time spent driving at 40 kmh = 20/40 = 1/2 hour And time spent driving at 20 kmh = 30/20 = 3/2 hours So, TOTAL travel time = 1/2 + 3/2 = 4/2 = 2 hours Average speed = 50/2 = 25 kmh Answer: C RELATED VIDEO _________________ Brent Hanneson – Founder of gmatprepnow.com Director Joined: 21 May 2013 Posts: 646 Re: John traveled the entire 50 km trip. If he travelled the first 20 km o [#permalink] ### Show Tags 02 Mar 2018, 09:28 MathRevolution wrote: [GMAT math practice question] John traveled the entire 50 km trip. If he traveled the first 20 km of the trip at a constant rate 40 km per hour and the remaining trip at a constant rate 20 km per hour, what is his average speed, in km per hour? A. 20 km/h B. 23 km/h C. 25 km/h D. 26 km/h E. 27 km/h Average Speed= Total distance traveled/Total time taken =50/(20/40+30/20) =50/2=25 Answer C Math Revolution GMAT Instructor Joined: 16 Aug 2015 Posts: 5577 GMAT 1: 800 Q59 V59 GPA: 3.82 Re: John traveled the entire 50 km trip. If he travelled the first 20 km o [#permalink] ### Show Tags 04 Mar 2018, 19:26 => Ave Speed = ( Total Distance ) / ( Total Time ) The total distance = $$50 km$$. Total time is $$\frac{20}{40} + \frac{30}{20} = 0.5 + 1.5 = 2$$ The average speed is $$\frac{50}{2} = 25.$$ Therefore, the answer is C. Answer : C _________________ MathRevolution: Finish GMAT Quant Section with 10 minutes to spare The one-and-only World’s First Variable Approach for DS and IVY Approach for PS with ease, speed and accuracy. "Only$99 for 3 month Online Course"
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Joined: 15 Oct 2016
Posts: 31
Re: John traveled the entire 50 km trip. If he travelled the first 20 km o [#permalink]

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04 Mar 2018, 19:37
MathRevolution wrote:
[GMAT math practice question]

John traveled the entire 50 km trip. If he traveled the first 20 km of the trip at a constant rate 40 km per hour and the remaining trip at a constant rate 20 km per hour, what is his average speed, in km per hour?

A. 20 km/h
B. 23 km/h
C. 25 km/h
D. 26 km/h
E. 27 km/h

Average speed = total distance / total time = 50 / (20/40 + 30/20) = 50 / (1/2 + 3/2) = 25
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Re: John traveled the entire 50 km trip. If he travelled the first 20 km o [#permalink]

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05 Mar 2018, 07:10
MathRevolution wrote:
[GMAT math practice question]

John traveled the entire 50 km trip. If he traveled the first 20 km of the trip at a constant rate 40 km per hour and the remaining trip at a constant rate 20 km per hour, what is his average speed, in km per hour?

A. 20 km/h
B. 23 km/h
C. 25 km/h
D. 26 km/h
E. 27 km/h

Time for travelling first 20 Kms = 0.50 Hr
Time for travelling first 30 Kms = 1.50 Hr

Total time taken = 2.00 Hrs

So, Average speed in kmph is $$\frac{50}{2} = 25kmph$$, Answer must be (C)
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Abhishek....

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Re: John traveled the entire 50 km trip. If he travelled the first 20 km o   [#permalink] 05 Mar 2018, 07:10
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